Sortix cross-volatile manual
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NAME
form — form libraryLIBRARY
Curses Form Library (libform, -lform)DESCRIPTION
The form library provides a terminal independent form system using the curses(3) library. Before using the form functions the terminal must be set up by curses(3) using the initscr() function or similar. Programs using form functions must be linked with the curses(3) library -lcurses.Defining default attributes for forms and fields
The form library allows any settable attribute or option of both the form and field objects to be defined such that any new form or field automatically inherits the value as default. Setting the default value will not affect any field or form that has already been created but will be applied to subsequent objects. To set the default attribute or option the set routine is passed a NULL pointer in the field or form parameter when calling the set routine. The current default value can be retrieved by calling the get routine with a NULL pointer for the field or form parameter.RETURN VALUES
Any function returning a string pointer will return NULL if an error occurs. Functions returning an integer will return one of the following:| E_OK |
The function was successful. |
| E_SYSTEM_ERROR |
There was a system error during the call. |
| E_BAD_ARGUMENT |
One or more of the arguments passed to the function was incorrect. |
| E_POSTED |
The form is already posted. |
| E_CONNECTED |
A field was already connected to a form. |
| E_BAD_STATE |
The function was called from within an initialization or termination routine. |
| E_NO_ROOM |
The form does not fit within the subwindow. |
| E_NOT_POSTED |
The form is not posted. |
| E_UNKNOWN_COMMAND |
The form driver does not recognize the request passed to it. |
| E_NOT_SELECTABLE |
The field could not be selected. |
| E_NOT_CONNECTED |
The field is not connected to a form. |
| E_REQUEST_DENIED |
The form driver could not process the request. |
| E_INVALID_FIELD |
The field is invalid. |
| E_CURRENT |
The field is the active one on the form. |
NOTES
This implementation of the forms library does depart in behavior subtly from the original AT&T implementation. Some of the more notable departures are:- field wrapping
- For multi-line fields the data will be wrapped as it is entered, this does not happen in the AT&T implementation.
- buffer 0
- In this implementation, the contents of buffer 0 are always current regardless of whether the field has been validated or not.
- circular fields
- In the AT&T implementation fields are circular on a page, that is, a next field from the last field will go to the first field on the current page. In this implementation a next field request on the last field of a page will result in the forms library positioning the cursor on the first field of the next page. If the field is the last field in the form then going to the next field will be denied, in the AT&T it would result in the cursor being placed on the first field of the first page.
- buffer returns
- In this implementation only the data entered by the user in the form field will be returned, unlike the AT&T library which would return the contents of the field padded to the size of the field with the pad character.
- The TAB character
- The handling of the TAB character in fields varies between implementations. In ncurses attempting to set a field contents with a string containing a TAB will result in an error and will not allow a TAB to be entered into a field. The AT&T library statically converts tabs to the equivalent number of spaces when the field buffer is set but the form driver will not allow a TAB to be inserted into the field buffer. This implementation allows TAB when setting the field buffer and also will allow TAB to be inserted into a field buffer via the form driver and correctly calculates the cursor position allowing for expansion of the TAB character.
- set_field_printf
- This function is a NetBSD extension and must not be used in portable code.
- O_REFORMAT
- This field option is a NetBSD extension and must not be used in portable code.